1. Field of the Invention
This invention concerns wear resistant lubricant additives, and more particularly to ethylene/.alpha.-olefin polymer grafted with perfluoro-substituted, ethylenically-unsaturated epoxides and reacted with perfluoro-substituted nucleophiles, which give enhanced wear resistance to lubricating oils.
2. Description of Background Information
Polytetrafluoroethylene (PTFE) materials, such as oligomeric waxes or oils of PTFE, have been used as anti-wear additives to lubricating oils. These and other wear resistant additives are designed to reduce friction and reduce wear of lubricated systems, such as internal combustion engines. This results in less frequent replacement of worn or damaged parts and greater engine, e.g. fuel, efficiency. PTFE dispersions in lubricating oils are, for example, described in U.S. Pat. No. 3,933,656, U.S. Pat. No. 4,051,050, U.S. Pat. No. 4,098,710, U.S. Pat. No. 4,194,984, U.S. Pat. No. 4,224,173 and U.S. Pat. No. 4,284,518.
PTFE oils and waxes are generally not, however, soluble in lubricating oils. As a result, the use of PTFE materials in lubricating oils gives dispersions or suspensions in which the PTFE can settle out of the formulation. This results in greater wear, particularly during start-up operation.
Perfluoroaliphatic alcohols have been grafted, using various techniques, onto olefin polymers as, for example, described in U.S. Pat. No. 4,973,413, U.S. patent application Ser. No. 07/563,599 filed Aug. 6, 1990 and U.S. patent application Ser. No. 07/649,504 filed Feb. 1, 1991. These perfluorooligomeric-substituted polymers are completely soluble in a wide variety of solvents, including lubricating oils. The resulting lubricating oils possess anti-friction properties over a range of temperatures and operating conditions.
Lubricant additives made by reacting polyolefin, epoxy grafting agent and modified 1,3,4-thiadiazoles are described in U.S. patent application Ser. No. 07/576,807 filed Sep. 4, 1990.